Zn and Ge co-doped In2O3-based ceramics have been prepared by the spark plasma sintering (SPS) technique. Microstructure studies show that dense and fine-grained ceramic samples can be obtained at low temperature sintered by SPS, and the grain size is about 100–300 nm. These In2O3-based ceramics show higher electrical conductivity (~103 S/cm) as compared with the pure In2O3 (~50 S/cm). In addition, the samples also exhibited large power factor, especially the In1.98Zn0.01Ge0.01O3 sample ~ 7.5 × 10-4 W/mK2. The evaluated maximum ZT value is 0.20 at 973 K, which makes them promising materials to be used in thermoelectric devices.